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Apply Compiled Transform Function (Advanced Performance API)

Source: R/performance-helpers.R
apply_transform_xptr.Rd

Apply a user-defined C++ transform function to sample values, compiled via RcppXPtrUtils, instead of calling an R callback per sample. Requires the RcppXPtrUtils package.

Usage

apply_transform_xptr(sound, transform_func)

Arguments

sound

Sound object or external pointer

transform_func

External pointer from RcppXPtrUtils::cppXPtr()

Value

Sound object with transform function applied

Details

**ADVANCED API** - Requires RcppXPtrUtils package.

The transform function receives sample amplitude and returns transformed amplitude. Common transforms:

  • Clipping: `x > threshold ? threshold : (x < -threshold ? -threshold : x)`

  • Soft clipping: `tanh(x * gain)`

  • Rectification: `fabs(x)`

  • Squaring: `x * x`

Examples

# \donttest{
# Compiling a C++ transform function takes a few seconds
if (requireNamespace("RcppXPtrUtils", quietly = TRUE)) {
  soft_clip <- RcppXPtrUtils::cppXPtr(
    "double softclip(double x) { return tanh(x * 2.0); }",
    depends = character()
  )

sound <- Sound$create_tone(frequency = 220, duration = 0.3, sampling_rate =
 16000)
  clipped <- apply_transform_xptr(sound, soft_clip)
}
# }